This invention relates generally to gas turbine engines and, more particularly, to gas turbine engines including compressible flanges.
Gas turbine engine bleed air systems typically include a plurality of tubes connected with tube couplings. Because adverse operation of the bleed air system may reduce an efficiency of the gas turbine engine, typically such tube couplings are multi-piece assemblies that couple to provide a substantially leak-proof assembly.
Known tube couplings include a flange assembly including a pair of mating flanges, and a clamping band used to tighten the two mating flanges. The mating flanges include a compressible or crushable flange fabricated from a material that permits the compressible flange to deform when the clamping band is tightened to form a sealing contact. Because of the clamping force applied to ensure the sealing contact is formed, elastic limits of the compressible flange material often are exceeded and the compressible flange may deform. Thus, if the coupling is disassembled, the compressible flange may need repair to restore a suitable sealing surface.
Manual cold-working techniques that force the flange into alignment using a combination of a vise, a pry bar, a flat plate, and a hammer typically are used to restore compressible seals. The restoration process is time-consuming and often the cold-working causes local stress concentrations to develop within the flanges. Over time, the stress concentrations may cause cracks to develop within the flanges which warrant the replacement of the flange.
Other known techniques of repairing compressible seals include cutting the deformed flange from the coupling and welding a replacement flange to the deformed flange. Such cutting and welding operations are also time-consuming and labor intensive.
In an exemplary embodiment, a bend die assembly retrofits compressible flanges to permit the flanges to be reinstalled around tubes to form a sealing contact. The bend die assembly includes a base and a bend die. The base includes a first body portion coupled to a second body portion to define a cavity. The bend die includes a base portion, a body portion, and a head portion, and is secured within the bend die assembly cavity after the bend die assembly first and second body portions are coupled. The bend die head portion receives the compressible flange and includes a plurality of segments that are expandable radially outwardly and are contoured to substantially conform to a contour of the compressible flange.
In use, the compressible flange is attached to the bend die assembly such that the bend die head portion is received within the compressible flange and the bend die body portion aligns the flange with respect to the bend die assembly. The bend die head portion segments are then forced radially outward to contact the compressible seal. As the bend die head portion segments contact the compressible seal, the seal is retrofitted, such that the compressible flange may be re-installed around a tube for sealing contact.